Using laser irradiation to shape optical surfaces is well known in the art. For instance, U.S. Pat. No. 4,194,814 teaches a method for forming indicia on a contact lens using a laser. In particular, this patent teaches that certain critical characteristics, i.e. wavelength and intensity to sublimate the surface of the contact lens in order to form smooth indicia.
U.S. Pat. No. 4,219,721 describes a method for using a laser to mark indicia on clear, polymethacrylate intraocular lenses. In particular, the patent teaches an apparatus for accomplishing high quality indicia.
U.S. Pat. No. 4,307,046 teaches using a CO.sub.2 laser to vaporize the surface of a contact lens blank and shape the blank into a lens. Essentially, this patent teaches using a laser beam as a cutting tool, much like a cutting tool used on a lathe which has been adapted to produce contact lenses. Thus this patented method depends upon the same techniques as those known in the prior contact lens manufacturing art.
U.S. Pat. No. 4,563,565 teaches a method for forming the edges of contact lenses. Again, critical to this process technology is the fluency of the laser, which is optimized by maximizing the ratio of heat of vaporization to heat absorbed by the polymer bulk. Furthermore, the process requires that the edge of the contact lens be indexed to the laser beam so that the lens can be rotated and thus effectively define the lens edge. The basic technology is similar to U.S. Pat. No. 4,307,046 except that it is specifically directed towards forming the edge of the lens rather than the surface of the lens.
U.S. Pat. No. 4,642,439 teaches a method for forming the edge of a contact lens made from silicone elastomer which employs a ring of laser radiation of the same radius as the desired dimension of the contact lens. The radius of said lens is fixed and the ring is employed only to form the edge of a lens. The method employs two laser rings to form the rounded edge of a contact lens. It does not teach using a ring of laser radiation to shape the optical surface or carrier surface of a lens.
U.S. Pat. No. 4,838,266 teaches process technology useful in modifying the surface of optical devices. The technology relies on the utilization of an attenuator which varies the energy distribution of the laser beam across the surface of the optical element being shaped. The technology depends upon fixing relative to one another, the laser beam, the optical article, and the attenuator.
U.S. Pat. No. 4,842,782 teaches a process technology using a laser to alter the surface of an optical device by way of employing a moving mask to vary the energy distribution across the surface of the optical surface.
None of the prior art techniques will produce axially symmetrical lenses and many of the techniques require orientation of the target specific to the laser beam in order to produce axial symmetry of any great degree.